Cinnamic acid derivative, polymer thereof, and liquid crystal alignment layer comprising cured product thereof

ABSTRACT

Provided is a liquid crystal alignment layer of which a constituent member is a compound represented by the general formula (I).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.14/129,848, filed on Dec. 27, 2013, which is a 371 of InternationalApplication No. PCT/JP2012/066294, filed on Jun. 26, 2012, which isbased upon and claims the benefit of priority from the prior JapanesePatent Application No. 2011-146043, filed on Jun. 30, 2011, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a compound, a polymer, a liquid crystalalignment layer, a liquid crystal display element, and an opticalanisotropic body.

The present application claims priority on Japanese Patent ApplicationNo. 2011-146043, filed on Jun. 30, 2011, the contents of which arehereby incorporated herein by reference.

BACKGROUND ART

An alignment layer for aligning a liquid crystal is important forkeeping the order of alignment of the liquid crystals and realizingoptical characteristics based on refractive index anisotropy of liquidcrystal molecules, and is an essential compositional member thatconstitutes a liquid crystal display element. Alignment of the liquidcrystals significantly affects display characteristics of liquid crystaldisplay elements, and thus various methods for aligning the liquidcrystal have been investigated. The liquid crystal display elements canbe broadly classified into two types, that is, a vertical alignment typeand a horizontal alignment type.

A liquid crystal display device (sometimes referred to as a VA modeliquid crystal display device) using a liquid crystal layer of avertical alignment type has been widely used in displays for itsexcellent display characteristics such as high contrast. However, sinceit cannot be said that the liquid crystal display device using a liquidcrystal layer of a vertical alignment type necessarily has sufficientviewing angle characteristics, various methods have been investigated toimprove the viewing angle characteristics. As a method for improving theviewing angle characteristics, a multi-domain vertical alignment mode(MVA mode) (incorporating an alignment division structure therein) hasbecome prevalent, which forms a plurality of liquid crystal domainshaving different alignment directions in one pixel. In the MVA mode, itis necessary to control the tilt alignment of the liquid crystalmolecules in order to form the alignment division structure, and as sucha method, a method in which a slit (opening) or a rib (projectionstructure) is provided in electrodes, is used. However, with the use ofthe slit or the rib, the slit or the rib is linear unlike a case where apretilt direction is defined by inserting liquid crystal molecules intotwo alignment films used in a TN mode used in the related art, and thus,the ability to control the alignment for the liquid crystal moleculesbecomes uneven within a pixel, whereby a problem of generation of adistribution in the response speeds arises.

In addition, there is another problem that a region provided with a slitor a rib exhibits decreased optical transmittance, resulting in adecrease in display luminance.

As another method for controlling the tilt alignment, there is discloseda polymer sustained alignment (PSA) technology in which photo- orthermo-polymerizable monomers are incorporated into a liquid crystal,the monomers being polymerized while tilting the liquid crystalmolecules by voltage application so that the tilt direction of theliquid crystal molecules is memorized (see PTL 1). This method canovercome the problem in the distribution of the response speeds or adecrease in the optical transmittance in the slit-and-rib method.However, this method faces problems such as changes in characteristicscaused by the addition of monomers in the liquid crystal material,difficulty in controlling the process, and adverse effects of theresidual monomers.

In order to avoid these problems, it is preferable even for the VA modeliquid crystal display device to form an alignment division structure bycontrolling the tilt alignment with an alignment film. As a method ofproviding an ability to control the tilt alignment on the verticalalignment film, there is a rubbing method, in which an alignment filmmade of a polyimide or the like is applied onto a substrate, and thenthe alignment film is rubbed with rubbing cloth to control the alignmentdirection and the pretilt angle. However, it is difficult to form aprecise alignment division structure by the rubbing method, and thusproblems of static electricity caused by friction and generation ofimpurities arise.

Meanwhile, as one of liquid crystal display devices using a liquidcrystal layer of the horizontal alignment type, there is an IPS (InPlane Switching) mode liquid crystal display device. The IPS mode liquidcrystal display device has little dependency on viewing angles such asin contrast and color tone, and is widely used in displays due to itsexcellent display characteristics. In the IPS mode, in order to reduceviewing angle dependency in the black display and the colorreproducibility, a low pretilt angle of one degree or less on theelectrode surface is required. Even when achieving the horizontalalignment, a rubbing method as a general alignment method is used.However, when a horizontal alignment treatment is carried out by arubbing treatment with a polyimide alignment film, the pretilt angleprovided to the liquid crystal molecules exceeds one degree, and thus, aproblem that the display characteristics are deteriorated arises.

From these problems, in any alignment mode of the vertical alignmenttype and the horizontal alignment type, it is important to control thealignment direction and the pretilt angle using the alignment film so asto improve the display characteristics. As a method for controlling thetilt alignment with an alignment film, a photo-alignment method isknown, in addition to the methods using rubbing treatment (see PTL 2).In the photo-alignment method, a precise alignment division structurecan be formed easily by changing the illumination pattern of light, andstatic electricity or generation of impurities is difficult to occur, ascompared with the rubbing treatment since a non-contact treatment on thealignment film can be carried out, and thus, it is expected to solve theabove-described problems and to improve the display characteristics.

As the materials which can be a photo-alignment layer for the liquidcrystal display element, a compound having a photochemicallyisomerizable site, such as an azobenzene derivative (see PTL 3), acompound having a photochemically crosslinkable site, such as a cinnamicacid derivative, a coumarin derivative, and a chalcone derivative (seePTLs 4, 5, and 6), a compound causing an anisotropic photo-degradation,such as a polyimide derivative, and the like are known.

However, the photo-alignment method using these compounds has a problemsuch as a low voltage holding ratio (VHR), as compared with a case usingan ordinary alignment film. Therefore, various characteristics such asreliability, which allows realization of performance for controlling thetilt alignment of the liquid crystals and use in active matrix driving,are required, and photo-alignment layers for liquid crystals, whichsatisfy the requirements, have been demanded.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application, First Publication No.2003-149647

[PTL 2] Japanese Patent No. 2682771

[PTL 3] Japanese Unexamined Patent Application, First Publication No.H05-232473

[PTL 4] Japanese Unexamined Patent Application, First Publication No.H06-287453

[PTL 5] Japanese Unexamined Patent Application, First Publication No.H09-118717

[PTL 6] Japanese Unexamined Patent Application Publication (Translationof PCT Application) No. 2002-517605

SUMMARY OF INVENTION Technical Problem

The present invention has an object to provide a liquid crystalalignment layer which is efficiently provided with an alignment propertyat a low irradiation dose of polarized light during the production, andhas a superior ability to control the alignment of liquid crystals andthe pretilt angles, and a high voltage holding ratio (VHR); a polymerused for the liquid crystal alignment layer; a compound constituting thepolymer; a liquid crystal display element using the liquid crystalalignment layer; and an optical anisotropic body using the polymer.

Solution to Problem

The present inventors have made extensive studies on various materialsin order to achieve the above object, and as a result, they have foundthat a liquid crystal alignment layer which is efficiently provided withan alignment property at a low irradiation dose of polarized lightduring the production, and has a superior ability to control thealignment of the liquid crystals and the pretilt angles, and a highvoltage holding ratio (VHR) is obtained by applying a polymer obtainedfrom a specific cinnamic acid derivative onto a substrate, and curingit, thereby leading to the completion of the present invention.

The compound of the present invention is a compound represented by thegeneral formula (I).

(in which L represents a polymerizable group and Sp¹ and Sp² eachrepresent a spacer unit,

A⁰¹ and A⁰² each independently represent a group selected from the groupconsisting of:

(a) a trans-1,4-cyclohexylene group (one methylene group or two or morenon-adjacent methylene groups present in this group may be substitutedwith —O—, —NH—, or —S—),

(b) a 1,4-phenylene group (one or two or more —CH═'s present in thisgroup may be substituted with —N═), and

(c) a 1,4-cyclohexenylene group, a 2,5-thiophenylene group, a2,5-furanylene group, a 1,4-bicyclo(2.2.2)octylene group, anaphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, adecahydronaphthalene-2,6-diyl group, and a1,2,3,4-tetrahydronaphthalene-2,6-diyl group, in which the group (a),(b), or (c) may be each unsubstituted or may have one or more hydrogenatoms substituted with a fluorine atom, a chlorine atom, a cyano group,a methyl group, or a methoxy group,

X¹, X², Y¹ and Y² each independently represent a hydrogen atom, afluorine atom, a chlorine atom, a cyano group, or an alkyl group having1 to 20 carbon atoms, but a hydrogen atom in the alkyl group may besubstituted with a fluorine atom, and one CH₂ group or two or morenon-adjacent CH₂ groups may be substituted with —O—, —CO—O—, —O—CO—and/or —CH═CH—,

Z is represented by the general formula (IIa) or (IIb):

(in which the dashed line represents a bond to a carbon atom, to which Zis bonded, and

R¹ and R² each independently represent a hydrogen atom or a linear orbranched alkyl group having 1 to 30 carbon atoms, one —CH₂— group or twoor more non-adjacent —CH₂— groups in R¹ and R² may be substituted with—O—, —CO—, —CO—O—, —O—CO—, —CO—NH—, —NH—CO—, —NCH₃—, —CH═CH—, —CF═CF—,and/or —C≡C—, one or two or more —CH₂— groups in R¹ and R² may be eachindependently substituted with a cycloalkyl group with a 3- to8-membered ring, and a hydrogen atom in R¹ and R² may be substitutedwith an alkyl group having 1 to 20 carbon atoms, a cyano group, or ahalogen atom),

W represents —O— or —NR³—, in which R³ represents a hydrogen atom, alinear or branched alkyl group having 1 to 20 carbon atoms, or acycloalkyl group with a 3- to 8-membered ring, which may have the alkylgroup interposed therein as a linking group, a hydrogen atom in thealkyl group may be unsubstituted or may be substituted with a fluorineatom or a chlorine atom, a hydrogen atom in the cycloalkyl group may beunsubstituted or may be substituted with an alkyl group having 1 to 10carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorineatom, or a chlorine atom, and r and t each independently represent 1 or2).

The polymer of the present invention is a polymer constituted with acured product of a composition including the compound according to thepresent invention, in which the cured product has a structural unitrepresented by the general formula (V).

(in which Sp¹, Sp², A⁰¹, A⁰², X¹, X², Y¹, Y², W, Z, r, and t have thesame definitions as in the general formula (I), M_(b) and M_(d) eachrepresent a monomer unit of the polymer, y and w each represent a molarfraction of the copolymer, each satisfying 0<y≤1 and 0≤w<1, n represents4 to 100,000, the order in which M_(b) and M_(d) are arranged may be thesame as or different from that shown in the formula, and the monomerunits of M_(b) and M_(d) may be each independently constituted with oneor two or more different units).

The liquid crystal alignment layer of the present invention is a liquidcrystal alignment layer using the polymer according to the presentinvention.

The liquid crystal display element of the present invention is a liquidcrystal display element using the liquid crystal alignment layeraccording to the present invention.

The optical anisotropic body of the present invention is an opticalanisotropic body using the liquid crystal alignment layer according tothe present invention.

Advantageous Effects of Invention

By using the compound (cinnamic acid derivative) of the presentinvention and a polymer thereof, a liquid crystal alignment layer whichhas a superior ability to control the alignment of the liquid crystalsand the pretilt angles, and a high voltage holding ratio (VHR) can beproduced, which is efficiently provided with an alignment property at alow irradiation dose of polarized light. Since the liquid crystalalignment layer of the present invention has a high voltage holdingratio (VHR) with a superior ability to control the alignment of theliquid crystals and the pretilt angles, it can be used to efficientlyproduce a liquid crystal display element and a liquid crystal displaydevice, each exhibiting excellent display quality and reliability.Further, the optical anisotropic body of the present invention is usefulfor the production of an optical anisotropy film that can be used inoptical compensation or the like.

DESCRIPTION OF EMBODIMENTS

(Embodiment of Cinnamic Acid Derivative)

Specifically, the cinnamic acid derivative of the present invention ispreferably a structure represented by the general formula (I).

In the general formula (I), L represents a polymerizable group and Sp¹and Sp² each represent a spacer unit, A⁰¹ and A⁰² each independentlyrepresent a group selected from the group consisting of:

(a) a trans-1,4-cyclohexylene group (one methylene group or two or morenon-adjacent methylene groups present in this group may be substitutedwith —O—, —NH—, or —S—),

(b) a 1,4-phenylene group (one or two or more —CH═'s present in thisgroup may be substituted with —N═), and

(c) a 1,4-cyclohexenylene group, a 2,5-thiophenylene group, a2,5-furanylene group, a 1,4-bicyclo(2.2.2)octylene group, anaphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, adecahydronaphthalene-2,6-diyl group, and a1,2,3,4-tetrahydronaphthalene-2,6-diyl group,

in which the group (a), (b), or (c) may be each unsubstituted or mayhave one or more hydrogen atoms substituted with a fluorine atom, achlorine atom, a cyano group, a methyl group, or a methoxy group.

That is, A⁰¹ and A⁰² may each independently represent a 1,4-naphthylenegroup, a 2,6-naphthylene group, a pyridine-2,5-diyl group, apyrimidine-2,5-diyl group, a 2,5-thiophenylene group, a 2,5-furanylenegroup, or a 1,4-phenylene group, and these may be unsubstituted or oneor more hydrogen atoms of these groups may be substituted with afluorine atom, a chlorine atom, a methyl group, or a methoxy group.

X¹, X², Y¹ and Y² each independently represent a hydrogen atom, afluorine atom, a chlorine atom, a cyano group, or an alkyl group having1 to 20 carbon atoms, but a hydrogen atom in the alkyl group may besubstituted with a fluorine atom, and one CH₂ group or two or morenon-adjacent CH₂ groups in the alkyl group may be substituted with —O—,—CO—O—, —O—CO— and/or —CH═CH—.

Z is represented by the general formula (IIa) or (IIb), and

r and t each independently represent 1 or 2).

In the general formula (IIa) and (IIb), the dashed line represents abond to a carbon atom, to which Z is bonded.

R¹ represents a hydrogen atom or a linear or branched alkyl group having1 to 30 carbon atoms, preferably having 1 to 20 carbon atoms, or acycloalkyl group with a 3- to 8-membered ring, which may have the alkylgroup interposed therein as a linking group, a hydrogen atom in thealkyl group may be unsubstituted or may be substituted with a fluorineatom or a chlorine atom, a hydrogen atom in the cycloalkyl group may beunsubstituted or may be substituted with an alkyl group having 1 to 10carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluorineatom, or a chlorine atom.

That is, R¹ represents a linear or branched alkyl group having 1 to 30carbon atoms, one —CH₂— group or two or more —CH₂— groups in R¹ may beeach independently substituted with a cycloalkyl group with a 3- to8-membered ring, and a hydrogen atom in R¹ may be substituted with analkyl group having 1 to 20 carbon atoms, a cyano group, or a halogenatom.

R² represents a linear or branched alkyl group having 1 to 30 carbonatoms, or a cycloalkyl group with a 3- to 8-membered ring, which mayhave the alkyl group interposed therein as a linking group, a hydrogenatom in the alkyl group may be unsubstituted or may be substituted witha fluorine atom or a chlorine atom, and a hydrogen atom in thecycloalkyl group may be unsubstituted or may be substituted with analkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10carbon atoms, a fluorine atom, or a chlorine atom.

That is, R² represents a linear or branched alkyl group having 1 to 30carbon atoms, one —CH₂— group or two or more —CH₂— groups in R² may beeach independently substituted with a cycloalkyl group with a 3- to8-membered ring, and a hydrogen atom in R² may be substituted with analkyl group having 1 to 20 carbon atoms, a cyano group, or a halogenatom.

R¹ is preferably a linear or branched alkyl group having 1 to 30 carbonatoms, in which one —CH₂— group or two or more —CH₂— groups in R¹ may beeach independently substituted with a cycloalkyl group with a 3- to8-membered ring.

R² is preferably a linear or branched alkyl group having 1 to 30 carbonatoms, in which one —CH₂— group or two or more —CH₂— groups in R² may beeach independently substituted with a cycloalkyl group with a 3- to8-membered ring.

In the present specification and claims, “two or more non-adjacent CH₂groups” means “two or more CH₂ groups that are not adjacent to eachother”.

In the general formula (I), (IIa), or (IIb), in order to improve theliquid crystal alignment properties of the liquid crystal alignmentlayer of the present invention, A⁰¹ and/or A⁰² is/are preferably apyridine-2,5-diyl group, a pyrimidine-2,5-diyl group, or a 1,4-phenylenegroup.

Further, in order to improve the solubility of the polymer of thepresent invention, A⁰¹ and/or A⁰² is/are preferably a 1,4-naphthylenegroup, a 2,6-naphthylene group, a 2,5-thiophenylene group, or a2,5-furanylene group.

Further, in order to reduce the light irradiation dose required foraligning the liquid crystal in the liquid crystal alignment layer of thepresent invention, A⁰¹ and/or A⁰² is/are preferably a pyridine-2,5-diylgroup, a pyrimidine-2,5-diyl group, a 2,5-thiophenylene group, or a1,4-phenylene group.

Further, in order to realize photo-alignment at a longer wavelength inthe liquid crystal alignment layer of the present invention, A⁰¹ and/orA⁰² is/are preferably a pyrimidine-2,5-diyl group, a 2,5-thiophenylenegroup, a 2,6-naphthylene group, or a 2,5-furanylene group, and at leastone selected from X¹, X², Y¹ and Y² is preferably a fluorine atom, achlorine atom, or a cyano group.

Further, in order to improve the voltage holding ratio in the liquidcrystal alignment layer of the present invention, X¹, X², Y¹ and Y² areeach preferably a hydrogen atom, and R² are each preferably a linear orcyclic alkyl group having 1 to 12 carbon atoms.

In addition, in order to reduce the residual charges in the liquidcrystal alignment layer of the present invention, R² is preferably alinear or cyclic alkyl group having 1 to 6 carbon atoms.

In the compound represented by the general formula (I) of the presentinvention, X¹, X², Y¹ and Y² are each preferably a hydrogen atom. Thus,the voltage holding ratio in the liquid crystal alignment layer of thepresent invention using the polymer obtained by using the compound canbe improved.

A preferable compound of the present invention is the compound of thegeneral formula (I), in which A⁰¹ represents a 1,4-phenylene grouphaving one or more hydrogen atoms which may be substituted with afluorine atom, a chlorine atom, a methyl group, or a methoxy group.

By using the compound, a liquid crystal alignment layer, and a displayelement using the composition, each of which is efficiently providedwith an alignment property at a low irradiation dose of polarized lightduring the production of the liquid crystal alignment layer, a superiorability to control the alignment of the liquid crystals and the pretiltangles, and a high voltage holding ratio (VHR), can be obtained.

A preferable compound of the present invention is the compound of thegeneral formula (I), in which A⁰² represents a 1,4-phenylene grouphaving one or more hydrogen atoms which may be substituted with afluorine atom, a chlorine atom, a methyl group, or a methoxy group.

By using the compound, a liquid crystal alignment layer, and a displayelement using the composition, each of which is efficiently providedwith an alignment property at a low irradiation dose of polarized lightduring the production of the liquid crystal alignment layer, a superiorability to control the alignment of the liquid crystals and the pretiltangles, and a high voltage holding ratio (VHR), can be obtained.

In the compound represented by the general formula (I) of the presentinvention, A⁰¹ and/or A⁰² is/are preferably a 1,4-phenylene group whichmay have one or more hydrogen atoms substituted with a fluorine atom, achlorine atom, a methyl group, or a methoxy group, and A⁰¹ and A⁰² aremore preferably a 1,4-phenylene group which has one or more hydrogenatoms substituted with a fluorine atom, a chlorine atom, a methyl group,or a methoxy group.

By using the compound, a liquid crystal alignment layer, and a displayelement using the composition, each of which has a superior ability tocontrol the alignment of the liquid crystals and the pretilt angles, anda high voltage holding ratio (VHR), can be obtained.

Since the compounds represented by the general formula (I) have apolymerizable substituent in the compound, the compounds can bepolymerized with each other. As the polymerizable substituent,specifically, in the general formula (I), L is preferably anysubstituent selected from the group consisting of the general formulae(III-1) to (III-17), and among these, the general formula (III-1),(III-2), (III-6), (III-7), or (III-13) is preferable, and the generalformula (III-1) or (III-2) is more preferable.

(in which the dashed line represents a bond to Sp¹ and R's independentlyrepresent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms).

In order to improve the solubility of the polymer of the presentinvention, the general formula (III-1), (III-2), (III-3), (III-6),(III-7), (III-8), (III-10), (III-12), (III-14), (III-16), or (III-17) ispreferable, and among these, the general formula (III-1), (III-2),(III-10), (III-12), or (III-17) is particularly preferable.

Incidentally, in order to improve the polymerization speed of thecompound of the present invention, the general formula (III-3), (III-8),(III-10), (III-12), (III-13), (III-14), (III-15), (III-16), or (III-17)is preferable, and among these, the general formula (III-3), (III-8),(III-10), (III-12), or (III-17) is more preferable.

Furthermore, in order to attain a narrow distribution of molecularweights of the polymer of the present invention, the general formula(III-2), (III-10), (III-11), or (III-12) is preferable.

Moreover, in order to improve the alignment stability in the liquidcrystal alignment layer of the present invention, the general formula(III-2), (III-4), (III-5), (III-7), (III-9), (III-13), (III-14), or(III-15) is preferable.

In addition, in order to improve the adhesion of the polymer of thepresent invention to a substrate, the general formula (III-1), (III-6),(III-7), (III-8), (III-9), (III-10), (III-12), (III-13), or (III-17) ispreferable, and among these, the general formula (III-6), (III-7),(III-8), or (III-13) is particularly preferable.

For the molecular weight distribution of the polymer of the presentinvention, Mw/Mn is preferably from 1.2 to 6.0, and more preferably from1.4 to 4.0.

The compound represented by the general formula (I) of the presentinvention is preferably a compound in which L is represented by thegeneral formula (III-1), (III-2), (III-6), (III-7), or (III-13). Byusing the compound, the above-described effects can be obtained.

The compound represented by the general formula (I) of the presentinvention is preferably the compound, in which L is represented by thegeneral formula (III-1) or (III-2).

By using the compound, a liquid crystal alignment layer, and a displayelement using and the composition, each of which has a superior abilityto control the alignment of the liquid crystals and the pretilt anglesand has effects such as a high voltage holding ratio (VHR), can beobtained.

In the general formula (I), Sp¹ and Sp² are each independentlypreferably a structure represented by the following general formula(IV):

(in which in Sp¹, the left dashed line represents a bond to L and theright dashed line represents a bond to A⁰¹, and in Sp², the left dashedline represents a bond to W and the right dashed line represents a bondto A⁰²,

in Sp¹ and Sp², Z¹, Z² and Z³ each independently represent a singlebond, —(CH₂)_(u)— (in which u represents 1 to 20), —OCH₂—, —CH₂O—,—COO—, —OCO—, —CH═CH—, —CF═CF—, —CF₂O—, —OCF₂—, —CF₂CF₂—, or —C≡C—, butone or more of the non-adjacent CH₂ groups in these groups may beindependently substituted with —O—, —CO—, —CO—O—, —O—CO—,—Si(CH₃)₂—O—Si(CH₃)₂—, —NR—, —NR—CO—, —CO—NR—, —NR—CO—O—, —O—CO—NR—,—NR—CO—NR—, —CH═CH—, —C≡C—, or —O—CO—O— (in which R's independentlyrepresent hydrogen or an alkyl group having 1 to 5 carbon atoms), and

A¹ and A² each independently represent a group selected from the groupconsisting of:

(a) a trans-1,4-cyclohexylene group (one methylene group or two or morenon-adjacent methylene groups present in this group may be substitutedwith —O—, —NH—, or —S—),

(b) a 1,4-phenylene group (one or two or more —CH═'s present in thisgroup may be substituted with —N═), and

(c) a 1,4-cyclohexenylene group, a 2,5-thiophenylene group, a2,5-furanylene group, a 1,4-bicyclo(2.2.2)octylene group, anaphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, adecahydronaphthalene-2,6-diyl group, and a1,2,3,4-tetrahydronaphthalene-2,6-diyl group, in which the group (a),(b), or (c) may be each unsubstituted or may have one or more hydrogenatoms substituted with a fluorine atom, a chlorine atom, a cyano group,a methyl group, or a methoxy group, and

p represents 0 or 1, and q represents 0, 1, or 2).

A¹ is preferably any group of a 1,4-naphthylene group, a 2,6-naphthylenegroup, a 2,5-thiophenylene group, or a 2,5-furanylene group, and one ormore hydrogen atoms in such any group may be substituted with a fluorineatom, a chlorine atom, a methyl group, or a methoxy group.

A² is preferably any group of a trans-1,4-cyclohexylene group, atrans-1,3-dioxane-2,5-diyl group, a 1,4-naphthylene group, a2,6-naphthylene group, a pyridine-2,5-diyl group, a pyrimidine-2,5-diylgroup, a 2,5-thiophenylene group, a 2,5-furanylene group, or a1,4-phenylene group, and one or more hydrogen atoms in such any groupmay be substituted with a fluorine atom, a chlorine atom, a methylgroup, or a methoxy group.

In the general formula (IV), Z¹, Z² and Z³ are each independentlypreferably a single bond, —(CH₂)_(u)— (in which u represents 1 to 20,one or more of the non-adjacent CH₂ groups may be independentlysubstituted with —O—, —CO—, —CO—O—, —O—CO—, —NR—, —NR—CO—, —CO—NR—,—NR—CO—NR—, —CH═CH—, —C≡C—, or —O—CO—O—, and R represents hydrogen, amethyl group, or an ethyl group), —OCH₂—, —CH₂O—, —COO—, —OCO—, —CH═CH—,—CF₂O—, —OCF₂—, or —C≡C—.

In the general formula (IV), Z¹, Z² and Z³ are each independently morepreferably a single bond, —(CH₂)_(u)— (in which u represents 1 to 20,and one or more of the non-adjacent CH₂ groups may be independentlysubstituted with —O—, —CO—O—, —O—CO—, —CH═CH—, or —C≡C—), —OCH₂—,—CH₂O—, —COO—, —OCO—, —CH═CH—, or —C≡C—.

In the general formula (IV), Z¹, Z² and Z³ are each independentlyparticularly preferably a single bond, —(CH₂)_(u)— (in which urepresents 1 to 20, and one or more of the non-adjacent CH₂ groups maybe independently substituted with —O—, —CO—O—, —O—CO—, —CH═CH—, or—C≡C—), —OCH₂—, —CH₂O—, —COO—, —OCO—, —CH═CH—, or —C≡C—.

Here, “one or more of the non-adjacent CH₂ groups” mean “one or more CH₂groups that are not adjacent to each other”.

In the general formula (IV), q is preferably 0.

In the general formula (IV), p is preferably 0.

In the general formula (IV), A¹ and A² are each independently preferablyany group of a trans-1,4-cyclohexylene group, atrans-1,3-dioxane-2,5-diyl group, a 1,4-naphthylene group, a2,6-naphthylene group, a pyridine-2,5-diyl group, a pyrimidine-2,5-diylgroup, or a 1,4-phenylene group. A hydrogen atom of these groups may beunsubstituted or one or more hydrogen atoms of these groups may besubstituted with a fluorine atom, a chlorine atom, a methyl group, or amethoxy group.

In the general formula (IV), A¹ and A² are each independently morepreferably any group of a trans-1,4-cyclohexylene group, a2,6-naphthylene group, a pyridine-2,5-diyl group, a pyrimidine-2,5-diylgroup, or a 1,4-phenylene group. A hydrogen atom of these groups may beunsubstituted or one or more hydrogen atoms of these groups may besubstituted with a fluorine atom, a chlorine atom, a methyl group, or amethoxy group.

In the general formula (IV), A¹ and A² are each independentlyparticularly preferably any group of a trans-1,4-cyclohexylene group, a2,6-naphthylene group, or a 1,4-phenylene group. A hydrogen atom ofthese groups may be unsubstituted or one or more hydrogen atoms of thesegroups may be substituted with a fluorine atom, a methyl group, or amethoxy group.

In order to improve the liquid crystal alignment property in the liquidcrystal alignment layer of the present invention, in the general formula(IV), Z¹, Z² and Z³ are each independently preferably a single bond,—(CH₂)_(u)— (in which u represents 1 to 8 and one or two of thenon-adjacent CH₂ groups may be independently substituted with —O—,—CO—O—, —O—CO—, —Si(CH₃)₂—O—Si(CH₃)₂—, —CH═CH—, or —C≡C—), —COO—, —OCO—,—CH═CH—, —CF═CF—, or —C≡C—, and A¹ and A² are each independentlypreferably a trans-1,4-cyclohexylene group, a trans-1,3-dioxane-2,5-diylgroup, a pyridine-2,5-diyl group, a pyrimidine-2,5-diyl group, a2,5-thiophenylene group, or a 1,4-phenylene group.

Furthermore, in order to improve the thermal stability of the alignmentin the liquid crystal alignment layer of the present invention, in thegeneral formula (IV), Z¹, Z² and Z³ are each independently preferably—NR—CO—, —CO—NR—, —NR—CO—O—, —O—CO—NR—, —NR—CO—NR—, or —O—CO—O—, A¹ andA² are each independently preferably a 1,4-naphthylene group, a2,6-naphthylene group, a pyridine-2,5-diyl group, a pyrimidine-2,5-diylgroup, a 2,5-thiophenylene group, a 2,5-furanylene group, or a1,4-phenylene group.

Moreover, in order to improve the solubility of the polymer of thepresent invention, Z¹, Z² and Z³ are each independently preferably—OCH₂—, —CH₂O—, —CF₂O—, —OCF₂—, —CF₂CF₂—, —NR—, or —CO—, A¹ and A² areeach independently preferably a trans-1,4-cyclohexylene group, a1,4-naphthylene group, a 2,6-naphthylene group, or a 2,5-furanylenegroup.

In order to improve the ability to control the alignment of the liquidcrystals and the pretilt angles in the liquid crystal alignment layer ofthe present invention and reduce the irradiation dose of polarized lightto provide an alignment property during the production, in the generalformula (IV), preferably, p and q are 0, Z¹ is —(CH₂)_(u)— (in which urepresents 1 to 8, and one or two of the non-adjacent CH₂ groups may beindependently substituted with —O—, —CO—O—, —O—CO—,—Si(CH₃)₂—O—Si(CH₃)₂—, —CH═CH—, —C≡C—), —COO—, —OCO—, —CH═CH—, —CF═CF—,or —C≡C—.

Sp¹ and Sp² represented by the general formula (IV) are eachindependently preferably, for example, those represented by thefollowing chemical formulae (Sp-a-1) to (Sp-ad-9). Among these chemicalformulae, the left dashed line represents a bond to L or a bond to W andthe right dashed line represents a bond to A⁰¹ or a bond to A⁰².

Among these, those represented by the chemical formulae (Sp-a-6) to(Sp-a-16), the chemical formulae (Sp-b-3) to (Sp-b-10), the chemicalformulae (Sp-c-3) to (Sp-c-10), the chemical formulae (Sp-d-3) to(Sp-d-12), the chemical formulae (Sp-k-4) to (Sp-k-7), the chemicalformulae (Sp-1-13) to (Sp-1-17), the chemical formulae (Sp-o-3) to(Sp-o-14), the chemical formulae (Sp-p-2) to (Sp-p-13), the chemicalformulae (Sp-s-1) to (Sp-s-8), the chemical formulae (Sp-t-1) to(Sp-t-8), the chemical formulae (Sp-y-1) to (Sp-y-9), and the chemicalformulae (Sp-aa-1) to (Sp-aa-9) are more preferable.

A preferable compound of the present invention is the compound of thegeneral formula (I), in which Sp′ represents a linear or branchedalkylene group having 1 to 20 carbon atoms, or the alkylene group havingone or more CH₂ groups which are not adjacent to each other substitutedwith —O— or —COO—.

By using the compound, a liquid crystal alignment layer, and a displayelement using the composition, each of which is efficiently providedwith an alignment property at a low irradiation dose of polarized lightduring the production of the liquid crystal alignment layer, and has asuperior ability to control the alignment of the liquid crystals and thepretilt angles, and a high voltage holding ratio (VHR), are obtained.

A preferable compound of the present invention is the compound of thegeneral formula (I), in which Sp² represents a linear or branchedalkylene group having 1 to 20 carbon atoms, or the alkylene group havingone or more CH₂ groups which are not adjacent to each other substitutedwith —O— or —COO—.

By using the compound, a liquid crystal alignment layer, and a displayelement using the composition, each of which is efficiently providedwith an alignment property at a low irradiation dose of polarized lightduring the production of the liquid crystal alignment layer, and has asuperior ability to control the alignment of the liquid crystals and thepretilt angles, and a high voltage holding ratio (VHR), are obtained.

A preferable compound of the present invention is the compound havingSp′ and Sp², each represented by the general formula (IV), in which pand q in the general formula (IV) are 0, and in Sp¹ and Sp², Z¹ is—(CH₂)_(u)— (in which u represents 1 to 8, and one or two of thenon-adjacent CH₂ groups may be independently substituted with —O—,—CO—O—, —O—CO—, —Si(CH₃)₂—O—Si(CH₃)₂—, —CH═CH—, or —C≡C—), —COO—, —OCO—,—CH═CH—, —CF═CF—, or —C≡C—.

By using the compound, a liquid crystal alignment layer, and a displayelement using the composition, each of which is efficiently providedwith an alignment property at a low irradiation dose of polarized lightduring the production of the liquid crystal alignment layer, and has asuperior ability to control the alignment of the liquid crystals and thepretilt angles, and a high voltage holding ratio (VHR), are obtained.

A more preferable compound of the present invention is the compoundhaving Sp′ and Sp², each represented by the general formula (IV), inwhich p and q in the general formula (IV) are 0, and in both of Sp¹ andSp², Z¹ is —(CH₂)_(u)— (in which u represents 1 to 8, and one or two ofthe non-adjacent CH₂ groups may be independently substituted with —O—,—CO—O—, —O—CO—, —Si(CH₃)₂—O—Si(CH₃)₂—, —CH═CH—, or —C≡C—).

By using the compound, a liquid crystal alignment layer, and a displayelement using the composition, each of which is efficiently providedwith an alignment property at a low irradiation dose of polarized lightduring the production of the liquid crystal alignment layer, and has asuperior ability to control the alignment of the liquid crystals and thepretilt angles, and a high voltage holding ratio (VHR), are obtained.

(Embodiments of Polymer)

The liquid crystal alignment layer of the present invention is obtainedby forming a layer of a polymer for a liquid crystal alignment layer onthe surface of a substrate used for aligning the liquid crystal, andirradiating it with light to conduct crosslinking and/or isomerization.The liquid crystal alignment layer of the present invention is producedusing a cured product of the cinnamic acid derivative or a compositioncontaining the cinnamic acid derivative. The cured product is preferablya polymer having a structural unit represented by the following generalformula (V). As specific embodiments or examples thereof, thosedescribed as follows are preferable.

(in which Sp², Sp², A⁰¹, A⁰², X¹, X², Y¹, Y², W, Z, r, and t have thesame definitions as in the general formula (I), M_(b) and M_(d) eachrepresent a monomer unit of the polymer, y and w each represent a molarfraction of the copolymer, each satisfying 0<y≤1 and 0≤w<1, n represents4 to 100,000, the order in which M_(b) and M_(d) are arranged may be thesame as or different from that shown in the formula, and the monomerunits of M_(b) and M_(d) may be each independently constituted with oneor two or more different units).

The polymer of the present invention can be preferably used to form aliquid crystal alignment layer for a horizontal alignment mode orvertical alignment mode liquid crystal display element, or to form aliquid crystal alignment layer for an optical anisotropic body. Further,the obtained liquid crystal alignment layer can be preferably used inthe horizontal alignment mode or vertical alignment mode liquid crystaldisplay element.

In the present specification and claims, the “monomer unit (M_(b))” andthe “monomer unit (M_(d))” are sometimes abbreviated as “M_(b)” and“M_(d)”, respectively.

In the general formula (V), a hydrogen atom of M_(b) is substituted withSp′ and thus Sp¹ is bonded to M_(b).

M_(b) and M_(d) may be the same as, except that Sp¹ is bonded to M_(b),or different from each other and a known monomer unit can be used whilenot being particularly limited. Further, the sequencing order andrandomness of the monomer units (M_(b) and M_(d)) in the polymer are notparticularly limited.

In addition, as M_(b) and M_(d), each independently, one kind of themonomer unit or combination of two or more kinds of the monomer unitscan be used. In this case, they are preferably used to a degree whichdoes not interfere with the effects exerted by the polymer as a liquidcrystal alignment film.

In the general formula (V), M_(b) is preferably any one or more selectedfrom the group consisting of the following general formulae (QIII-A-1)to (QIII-A-17).

(in which the dashed line represents a bond to Sp¹, R's independentlyrepresent hydrogen or an alkyl group having 1 to 5 carbon atoms, and anyhydrogen atom in each of the structures may be substituted with afluorine atom, a chlorine atom, a methyl group, or a methoxy group).

In the general formula (V), M_(d) is preferably any one or more selectedfrom the group consisting of the following general formulae (QIII-1) to(QIII-17).

(in which the dashed line represents a bond to a hydrogen atom or amonovalent organic group, R's independently represent hydrogen or analkyl group having 1 to 5 carbon atoms, and any hydrogen atom in each ofthe structures may be substituted with a fluorine atom, a chlorine atom,a methyl group, or a methoxy group).

Examples of the monovalent organic group include hydrogen, an alkylgroup having 1 to 20 carbon atoms (any hydrogen atom in the alkyl groupmay be substituted with a fluorine atom, a chlorine atom, a methylgroup, or a methoxy group, and one CH₂ group or two or more non-adjacentCH₂ groups in the alkyl group may be substituted with —O—, —CO—O—,—O—CO—, and/or —CH═CH—). For example, the number of carbon atoms of thealkyl group may be, for example, 1 to 10, if necessary, or may be, forexample, 1 to 6 or 1 to 3.

Incidentally, examples of the monovalent organic group include atrans-1,4-cyclohexylene group, a trans-1,3-dioxan-2,5-yl group, a1,4-naphthylene group, a 2,6-naphthylene group, a 2,5-pyridyl group, a2,5-pyrimidyl group, a 2,5-thiophenylene group, a 2,5-furanylene group,or a 1,4-phenylene group (any hydrogen atom in each of the structuresmay be substituted with a fluorine atom, a chlorine atom, a methylgroup, or a methoxy group).

Moreover, particularly, in order to obtain an alignment layer forvertical alignment, examples of the monovalent organic group includethose of the general formula (QIV). That is, in the general formulae(QIII-1) to (QIII-17), the monovalent organic group may be representedby the general formula (QIV).

[Chem. 45]-S_(a)-V_(a)  (QIV)

(in which the dashed line represents a bond to a monomer unit (M_(d)),S_(a) represents a spacer unit, and V_(a) represents a moiety thatstabilizes the vertical alignment).

As S_(a), a spacer unit represented by the general formula (IV) asdescribed above may be used.

V_(a) is preferably a structure represented by the following generalformula (VI).

In the general formula (VI), the dashed line represents a bond to S_(a),

Z⁴, Z⁵, Z⁶ and Z⁷ each independently represent a single bond,—(CH₂)_(u)— (in which u represents 1 to 20), —OCH₂—, —CH₂O—, —COO—,—OCO—, —CH═CH—, —CF═CF—, —CF₂O—, —OCF₂—, —CF₂CF₂—, or —C≡C— but one ormore of the non-adjacent CH₂ groups in these substituents may beindependently substituted with —O—, —CO—, —CO—O—, —O—CO—,—Si(CH₃)₂—O—Si(CH₃)₂—, —NR—, —NR—CO—, —CO—NR—, —NR—CO—O—, —O—CO—NR—,—NR—CO—NR—, —CH═CH—, —C≡C—, or —O—CO—O— (in which R's independentlyrepresent hydrogen or an alkyl group having 1 to 5 carbon atoms),

A³, A⁴, A⁵ and A⁶ each independently represent a group selected from thegroup consisting of:

(a) a trans-1,4-cyclohexylene group (one methylene group or two or morenon-adjacent methylene groups present in this group may be substitutedwith —O—, —NH—, or —S—),

(b) a 1,4-phenylene group (one or two or more —CH═'s present in thisgroup may be substituted with —N═), and

(c) a 1,4-cyclohexenylene group, a 2,5-thiophenylene group, a2,5-furanylene group, a 1,4-bicyclo(2.2.2)octylene group, anaphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, adecahydronaphthalene-2,6-diyl group, and a1,2,3,4-tetrahydronaphthalene-2,6-diyl group, in which the group (a),(b), or (c) may be each unsubstituted or may have one or more hydrogenatoms substituted with a fluorine atom, a chlorine atom, a cyano group,a methyl group, or a methoxy group,

r1, s1, t1, and u1 each independently represent 0 or 1, and

R¹² represents hydrogen, fluorine, chlorine, a cyano group, or an alkylgroup having 1 to 20 carbon atoms, a hydrogen atom in the alkyl groupmay be substituted with a fluorine atom, and one CH₂ group or two ormore non-adjacent CH₂ groups in the alkyl group may be substituted with—O—, —CO—O—, —O—CO— and/or —CH═CH—)).

Z⁴, Z⁵, Z⁶ and Z⁷ are each independently preferably a single bond,—(CH₂)_(u)— (in which u represents 1 to 12, one or more of thenon-adjacent CH₂ groups may be independently substituted with —O—, —CO—,—CO—O—, —O—CO—, —NR—CO—, —CO—NR—, —NR—CO—NR—, —CH═CH—, —C≡C—, or—O—CO—O—, and R's independently represent hydrogen, a methyl group, oran ethyl group), —OCH₂—, —CH₂O—, —COO—, —OCO—, —CH═CH—, —CF₂O—, —OCF₂—,or —C≡C—.

A³, A⁴, A⁵ and A⁶ each independently preferably represent atrans-1,4-cyclohexylene group, a trans-1,3-dioxane-2,5-diyl group, a1,4-naphthylene group, a 2,6-naphthylene group, a pyridine-2,5-diylgroup, a pyrimidine-2,5-diyl group, a 2,5-thiophenylene group, a2,5-furanylene group, or a 1,4-phenylene group. A³, A⁴, A⁵ and A⁶ eachindependently preferably represent a trans-1,4-cyclohexylene group, a2,6-naphthylene group, a pyridine-2,5-diyl group, a pyrimidine-2,5-diylgroup, or a 1,4-phenylene group. Preferably, these groups areunsubstituted or have one or more hydrogen atoms substituted with afluorine atom, a chlorine atom, a methyl group, or a methoxy group.

For r1, s1, t1, and u1, r1+s1+t1+u1 is preferably from 0 to 3.

R¹² is preferably a structure represented by hydrogen, fluorine,chlorine, a cyano group, or an alkyl group having 1 to 18 carbon atoms(one CH₂ group or two or more non-adjacent CH₂ groups in the alkyl groupmay be substituted with —O—, —CO—O—, —O—CO—, and/or —CH═CH—).

In order to improve the liquid crystal alignment property in the liquidcrystal alignment layer of the present invention, Z⁴, Z⁵, Z⁶ and Z⁷ areeach independently preferably a single bond, —(CH₂)_(u)— (in which urepresents 1 to 8, and one or two of the non-adjacent CH₂ groups may beindependently substituted with —O—, —CO—O—, —O—CO—,—Si(CH₃)₂—O—Si(CH₃)₂—, —CH═CH—, or —C≡C—), —COO—, —OCO—, —CH═CH—,—CF═CF—, or —C≡C— and A³, A⁴, A⁵ and A⁶ are each independentlypreferably a trans-1,4-cyclohexylene group, a trans-1,3-dioxane-2,5-diylgroup, a pyridine-2,5-diyl group, a pyrimidine-2,5-diyl group, a2,5-thiophenylene group, or a 1,4-phenylene group.

Moreover, in order to improve the thermal stability of alignment in theliquid crystal alignment layer of the present invention, Z⁴, Z⁵, Z⁶ andZ⁷ are each independently preferably —NR—CO—, —CO—NR—, —NR—CO—O—,—O—CO—NR—, —NR—CO—NR—, or —O—CO—O—, and A³, A⁴, A⁵ and A⁶ are eachindependently preferably a 1,4-naphthylene group, a 2,6-naphthylenegroup, a pyridine-2,5-diyl group, a pyrimidine-2,5-diyl group, a2,5-thiophenylene group, a 2,5-furanylene group, or a 1,4-phenylenegroup.

Furthermore, in order to improve the solubility of the polymer of thepresent invention, Z⁴, Z⁵, Z⁶ and Z⁷ are each independently preferably—OCH₂—, —CH₂O—, —CF₂O—, —OCF₂—, —CF₂CF₂—, —NR—, or —CO—, and A³, A⁴, A⁵and A⁶ are each independently preferably a trans-1,4-cyclohexylenegroup, a 1,4-naphthylene group, a 2,6-naphthylene group, or a2,5-furanylene group.

Furthermore, in order to provide a pretilt angle of 80 degrees or moreto the liquid crystal alignment layer of the present invention, Z⁴, Z⁵,Z⁶ and Z⁷ are each independently preferably a single bond, —OCH₂—,—CH₂O—, —COO—, —OCO—, and —C≡C—, A³, A⁴, A⁵ and A⁶ are eachindependently preferably a trans-1,4-cyclohexylene group, atrans-1,3-dioxane-2,5-diyl group, or a 1,4-phenylene group, and R¹² ispreferably an alkyl group having 1 to 20 carbon atoms, an alkoxy group,fluorine, a trifluoromethyl group, or a trifluoromethoxy group.

In the case of providing a pretilt angle of 80 degrees or more to theliquid crystal alignment layer of the present invention, as V_(a)represented by the general formula (VI), for example, compoundsrepresented by the following chemical formulae (VI-a-1) to (VI-q-10) areparticularly preferable. Among these chemical formulae, the dashed linerepresents a bond to S_(a).

Among these, the chemical formulae (VI-a-1) to (VI-a-15), the chemicalformulae (VI-b-11) to (VI-b-15), the chemical formulae (VI-c-1) to(VI-c-11), the chemical formulae (VI-d-10) to (VI-d-15), the chemicalformulae (VI-f-1) to (VI-f-10), the chemical formulae (VI-g-1) to(VI-g-10), the chemical formulae (VI-h-1) to (VI-h-10), the chemicalformulae (VI-j-1) to (VI-j-9), the chemical formulae (VI-1-1) to(VI-1-11), or the chemical formulae (VI-m-1) to (VI-m-11) are morepreferable.

In the polymer represented by the general formula (V) of the presentinvention, as M_(b) or M_(d), for example, acrylate, methacrylate,acrylamide, methacrylamide, maleic acid derivatives, siloxanes,epoxides, an acryloyloxy group, a methacryloyloxy group, a2-chloroacryloyloxy group, a 2-phenylacryloyloxy group, a2-phenyloxyacryloyloxy group, an acrylamide group, a methacrylamidegroup, a 2-chloromethacrylamide group, a 2-phenylacrylamide group, avinyloxy group, a styryl group, a vinyloxycarbonyl group, a maleimidegroup, maleic esters, fumaric esters, siloxanes, a vinyl group, or anepoxy group may be used.

[Preparation of Polymer for Alignment Layer]

The cinnamic acid derivative in the present invention may be used aloneas a material for the polymer, or the cinnamic acid derivative may beused in a composition formed by mixing other monomers with the cinnamicacid derivative. In the composition, it is possible to prepare thepolymer at an arbitrary mixing ratio of the cinnamic acid derivative andthe other monomers. For example, the ratio of the other monomersrelative to 100-fold moles of the cinnamic acid derivative is preferablyfrom 0.1-fold mole to 30-fold moles. Further, the other monomers arepreferably liquid crystalline compounds.

It is preferable that the material and the composition include a solventand/or a polymerization initiator.

The polymer of the present invention can be prepared by polymerizing thecinnamic acid derivative or the composition in the present invention.

During the polymerization, a polymerization initiator may be optionallyused, depending on the polymerization mode of the polymerizablefunctional group. Examples of the polymerization initiator include thoseas described in known publications such as “Synthesis and Reaction ofPolymers, edited by The Society of Polymer Science, Japan and publishedby Kyoritsu Shuppan Co., Ltd.”.

Examples of the thermal polymerization initiator in the radicalpolymerization include azo compounds such as azobisisobutyronitrile andperoxides such as benzoyl peroxide.

Examples of a photopolymerization initiator include aromatic ketonecompounds such as benzophenone, Michler's ketone, xanthone, andthioxanthone, quinones such as 2-ethylanthraquinone, acetophenonecompounds such as acetophenone, trichloroacetophenone,2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone,benzoin ether, 2,2-diethoxyacetophenone, and2,2-dimethoxy-2-phenylacetophenone, diketone compounds such as benzyland methylbenzoyl formate, acyloxime ester compounds such as1-phenyl-1,2-propanedione-2-(o-benzoyl)oxime, acylphosphine oxidecompounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, sulfurcompounds such as tetramethylthiuram and dithiocarbamate, organicperoxides such as benzoyl peroxide, and azo compounds such asazobisisobutyronitrile.

Further, examples of the thermal polymerization initiator used incationic polymerization include aromatic sulfonium salt compounds.

In addition, examples of the photopolymerization initiator includeorganic sulfonium salt compounds, iodonium salt compounds, andphosphonium compounds.

The amount of the polymerization initiator added is preferably from 0.1%by mass to 10% by mass, more preferably from 0.1% by mass to 6% by mass,and still more preferably from 0.1% by mass to 3% by mass in thecomposition. Further, a desired polymer can be synthesized by anaddition reaction to a polymer main chain, such as with a polysiloxanecompound.

The polymer in the present invention is obtained by first subjecting thematerials or the composition to a polymerization reaction in a reactormade of glass, stainless steel, or the like, and then purifying theresulting polymer. Preferable examples of the solvent which may beincluded in the materials or the composition include benzene, toluene,xylene, ethylbenzene, pentane, hexane, heptane, octane, cyclohexane,cycloheptane, methanol, ethanol, 1-propanol, 2-propanol, ethyleneglycol, ethylene glycol monomethyl ether, ethylene glycol dimethylether, 2-butanone, acetone, tetrahydrofuran, γ-butyrolactone,N-methyl-pyrrolidone, dimethyl sulfoxide, and dimethylformamide. Theorganic solvents may be used alone or in combination of two or morekinds thereof.

The polymer according to the present invention can also be obtained bydissolving the cinnamic acid derivative or the composition in a solvent,applying the solution onto a substrate to remove the solvent by drying,and conducting a polymerization reaction by heating or lightirradiation.

[Method for Forming Liquid Crystal Alignment Layer]

The ability to control the alignment of liquid crystal molecules and thestability of the alignment of the liquid crystal molecules against heatand light can be developed by irradiating the polymer in the presentinvention with light. The liquid crystal alignment layer obtained fromthe polymer of the present invention, which is obtained by conductinglight irradiation, may be referred to as a photo-alignment film.

An example of a method for producing the liquid crystal alignment layer(photo-alignment film) of the present invention is a method ofdissolving the polymer in a solvent, applying the solution onto asubstrate, and then irradiating the coating film with light to exhibitthe ability to control the alignment to afford a photo-alignment film.

The solvent used in dissolving the polymer is preferably a solvent thatdissolves but does not react with the polymer of the present inventionand other components optionally used. Examples of the solvent include1,1,2-trichloroethane, N-methylpyrrolidone, butoxyethanol,γ-butyrolactone, ethylene glycol, polyethylene glycol monomethyl ether,propylene glycol, 2-pyrrolidone, N,N-dimethylformamide, phenoxyethanol,tetrahydrofuran, dimethylsulfoxide, methyl isobutyl ketone, andcyclohexanone. The organic solvents may be used alone or in combinationof two or more kinds thereof.

Another method for producing the liquid crystal alignment layer(photo-alignment film) of the present invention is a method ofdissolving the cinnamic acid derivative or the composition of thepresent invention in a solvent, applying the solution onto a substrate,heating the coating film or irradiating the coating film with light toprepare a polymer, and further irradiating the polymer with light toexhibit the ability to control the alignment, thereby affording aphoto-alignment film.

As a solvent used for dissolving the cinnamic acid derivative or thecomposition, the same solvent as the solvent used for dissolving thepolymer may be used.

In the method for producing the liquid crystal alignment layer(photo-alignment film) of the present invention, preparation of thepolymer and exhibition of an ability to control the alignment may besimultaneously conducted by light irradiation. Further, preparation ofthe polymer and exhibition of an ability to control the alignment may beseparately conducted by a method of combining heating and lightirradiation or by a method of combining two or more light beams havingdifferent wavelengths.

In any of the methods of producing the liquid crystal alignment layer(photo-alignment film) of the present invention, an alignment film maybe preliminarily formed on a substrate and then a photo-alignment filmusing the cinnamic acid derivative, the composition, or the polymer ofthe present invention may be produced on the substrate so that thesubstrate may be provided with an ability to control the alignmentdirection and the alignment angle.

Examples of the material for the substrate include glass, silicon,polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and triacetyl cellulose. An electrode layer(conductive layer) such as Cr, Al, an ITO film composed of In₂O₃—SnO₂,and a NESA film composed of SnO₂ may be provided to this substrate. Forthe patterning of these electrode layers, a photoetching method may beapplied. Further, the electrode layers may also be patterned by, forexample, a method using a mask, in forming the electrode layers. Inaddition, a color filter layer or the like may also be formed on thesubstrate.

Examples of the method of applying a solution of the cinnamic acidderivative, the composition, or the polymer of the present inventiononto a substrate include spin coating, die coating, gravure coating,flexographic printing, and ink jet printing.

The concentration of the solid content in the solution used in theapplication is preferably 0.5% by weight to 10% by weight, and is morepreferably selected from this range by considering a method of applyingthe solution on the substrate, viscosity, volatility, or the like.

Further, the applied surface is preferably heated after the applicationso as to remove the solvent. The drying conditions are preferably 50° C.to 300° C., and more preferably 80° C. to 200° C. for preferably 2minutes to 200 minutes, and more preferably 2 minutes to 100 minutes.

In the case where the cinnamic acid derivative or the composition of thepresent invention is used, a polymer may be prepared on the substrate byconducting thermal polymerization by the heating treatment, and in thiscase, a polymerization initiator is preferably added to the material andthe composition. Alternatively, a polymer may be prepared byphotopolymerization through irradiating the composition with unpolarizedlight after removal of the solvent in the heating treatment, oralternatively, thermal polymerization and photopolymerization may becombined.

In the case of preparing the polymer by thermal polymerization on thesubstrate, the heating temperature may be any temperature sufficient forallowing the polymerization to proceed. Typically, the heatingtemperature is about 50° C. to 250° C., and more preferably about 70° C.to 200° C. Further, the polymerization initiator may or may not be addedto the composition.

In preparing the polymer by photopolymerization on the substrate,unpolarized ultraviolet light is preferably used for light irradiation.Moreover, a polymerization initiator is preferably incorporated into thecomposition. The irradiation energy is preferably 10 mJ/cm² to 8000mJ/cm², and more preferably 40 mJ/cm² to 5000 mJ/cm². The luminousintensity is preferably 2 mW/cm² to 1000 mW/cm², and more preferably 4mW/cm² to 500 mW/cm². The radiation wavelength preferably has a peak ina range of 250 nm to 450 nm.

Next, a photocrosslinking reaction is conducted on a coating filmcomposed of the polymer formed by the method, by applying linearpolarized light in the coated surface normal direction and applyingunpolarized or linear polarized light in an oblique direction and curingis conducted to exhibit an ability to control the alignment. Further,these irradiation methods may be combined. In order to form a desiredpretilt angle, irradiation with linear polarized light in an obliquedirection is preferable. Further, the oblique direction refers toinclination with respect to a direction parallel to the substratesurface and this angle of inclination is referred to as a pretilt angle.In the case where the film is used as the alignment film for verticalalignment, the pretilt angle is typically preferably 70° to 89.8°.Further, in the case where the film is used as an alignment film forhorizontal alignment, typically, the pretilt angle is preferably 1° to7°, and in an IPS mode, the pretilt angle is preferably 0° to 1°.

As the light used for irradiation when subjecting a coating filmcomposed of the polymer to curing (photocrosslinking reaction), therebyforming the film into a liquid crystal alignment layer (photo-alignmentfilm), for example, ultraviolet rays or visible rays containing lighthaving a wavelength of 150 nm to 800 nm may be used, and among these,ultraviolet rays having a wavelength of 270 nm to 450 nm areparticularly preferable.

Examples of the light source include a xenon lamp, a high-pressuremercury lamp, an ultrahigh-pressure mercury lamp, and a metal halidelamp. Linear polarized light is obtained by using a polarizing filterand a polarizing prism for light from these light sources. Further, theultraviolet light and visible light obtained from such light sources mayhave a wavelength range for irradiation restricted by using aninterference filter or a color filter.

In addition, the irradiation energy is preferably 15 mJ/cm² to 500mJ/cm², and more preferably 20 mJ/cm² to 300 mJ/cm². The luminousintensity is more preferably 2 mW/cm² to 500 mW/cm², and still morepreferably 5 mW/cm² to 300 mW/cm².

The thickness of the liquid crystal alignment layer (photo-alignmentfilm) to be formed is preferably about 10 nm to 250 nm, and morepreferably about 10 nm to 100 nm.

[Method for Producing Liquid Crystal Display Element]

A liquid crystal cell including a pair of substrates and a liquidcrystal composition sandwiched between the substrates, and a liquidcrystal display element using the same can be produced by using theliquid crystal alignment layer (photo-alignment film) formed by themethod as described above, for example, by the following manner.

By preparing two substrates on which the liquid crystal alignment layerin the present invention is formed and arranging liquid crystal betweenthe two substrates, a liquid crystal cell can be produced. Further, theliquid crystal alignment layer may be formed on only one of the twosubstrates.

Examples of a method for producing the liquid crystal cell include thefollowing methods.

First, two substrates are arranged so that the respective liquid crystalalignment layers face each other, and the peripheral portions of the twosubstrates are bonded with a sealing agent while maintaining aparticular space (cell gap) between the two substrates. Liquid crystalis poured into a cell gap defined by the substrate surfaces and thesealing agent to fill the cell gap, and the inlet hole is sealed toproduce a liquid crystal cell.

The liquid crystal cell may also be produced by a technique called a OneDrop Fill (ODF) process. The process can be conducted, for example, bythe following procedure. For example, an ultraviolet light-curablesealing agent is applied to a predetermined position on a substrate onwhich the liquid crystal alignment layer is formed, a liquid crystal isdropped onto the liquid crystal alignment layer, and another substrateis then bonded so that the liquid crystal alignment layers face eachother. Then, the entire surfaces of the substrates are irradiated withUV light to cure the sealing agent, thereby producing a liquid crystalcell.

Regardless of the method with which the liquid crystal cell is produced,the liquid crystal used is preferably heated to a temperature at whichthe liquid crystal transitions to an isotropic phase and then slowlycooled to room temperature so as to eliminate the alignment induced bythe flow during pouring.

For example, an epoxy resin may be used as the sealing agent.

In order to keep the cell gap constant, beads of silica gel, alumina,acrylic resin, or the like may be used as a spacer prior to bonding thetwo substrates. These spacers may be spread over the coating film of theliquid crystal alignment layer, or added to a sealing agent and then twosubstrates may be bonded.

For example, nematic-type liquid crystals may be used as the liquidcrystal.

For a vertical alignment-type liquid crystal cell, a liquid crystalhaving a negative dielectric anisotropy is preferable, and for example,dicyanobenzene-based liquid crystals, pyridazine-based liquid crystals,Schiff-base-based liquid crystals, azoxy-based liquid crystals,naphthalene-based liquid crystals, biphenyl-based liquid crystals, andphenylcyclohexane-based liquid crystals are used.

In the case of the horizontal alignment type liquid crystal cell, aliquid crystal having a positive dielectric anisotropy is preferable.For example, cyanobenzene-based liquid crystals, difluorobenzene-basedliquid crystals, trifluorobenzene-based liquid crystals,trifluoromethylbenzene-based liquid crystals,trifluoromethoxybenzene-based liquid crystals, pyrimidine-based liquidcrystals, naphthalene-based liquid crystals, biphenyl-based liquidcrystals, phenylcyclohexane-based liquid crystals, or the like are used.

A liquid crystal display element can be obtained by bonding a polarizingplate to an outer surface of the liquid crystal cell thus produced.Examples of the polarizing plate include a polarizing plate formed of an“H film” in which iodine has been absorbed while stretching and aligninga polyvinyl alcohol, and a polarizing plate having an H film sandwichedbetween cellulose acetate protective films.

The liquid crystal display element of the present invention thusproduced is excellent in various kinds of performance such as displaycharacteristics and reliability. Further, as the alignment mode of theliquid crystal display element, both a horizontal alignment mode and avertical alignment mode can be produced.

[Method for Producing Optical Anisotropic Body]

An optical anisotropic body may also be produced by applying apolymerizable liquid crystal composition onto the photo-alignment filmand polymerizing it while aligning the polymerizable liquid crystalmolecules in the polymerizable liquid crystal composition.

The polymerizable liquid crystal composition is a liquid crystalcomposition containing a polymerizable liquid crystal which exhibitsliquid crystal properties either alone or in a composition with anotherliquid crystal compound. Examples of such compounds include rod-shapedpolymerizable liquid crystal compounds having a rigid site, referred toas a mesogen in which a plurality of structures such as a 1,4-phenylyenegroup and a 1,4-cyclohexylene group are connected, and a polymerizablefunctional group such as a (meth)acryloyloxy group, a vinyloxy group,and an epoxy group, as described in the Handbook of Liquid Crystals(edited by D. Demus, J. W. Goodby, G W. Gray, H. W. Spiess, V. Vill,published by Wiley-VCH publishers, 1998), Kikan Kagaku Sosetsu No. 22,Liquid Crystal Chemistry (edited by Chemical Society of Japan, 1994), orJapanese Unexamined Patent Application, First Publication Nos.H07-294735, H08-3111, H08-29618, H11-80090, H11-148079, 2000-178233,2002-308831, and 2002-145830; rod-shaped polymerizable liquid crystalcompounds having a maleimide group as described in Japanese UnexaminedPatent Application, First Publication Nos. 2004-2373 and 2004-99446;rod-shaped polymerizable liquid crystal compounds having an allyl ethergroup as described in Japanese Unexamined Patent Application, FirstPublication No. 2004-149522; and for example, discotic polymerizablecompounds as described in the Handbook of Liquid Crystals, (edited by D.Demus, J. W. Goodby, G W. Gray, H. W. Spiess, V. Vill, published byWiley-VCH, 1998), Kikan Kagaku Sosetsu No. 22, Liquid Crystal Chemistry(edited by Chemical Society of Japan, 1994) or Japanese UnexaminedPatent Application, First Publication No. H07-146409. Among these, therod-shaped liquid crystal compounds having a polymerizable group arepreferable since a film having a low liquid crystal temperature rangewhich is in the vicinity of room temperature is easily fabricated.

EXAMPLES

The present invention will be described in further detail with referenceto Examples below, but the present invention is not limited to Examples.The structure of a compound was identified with a nuclear magneticresonance (NMR) spectrum, a mass spectrum (MS), or the like. Unlessotherwise noted, “parts” and “%” are on a mass basis.

Synthesis of Cinnamic Acid Derivative DiCin-1 Example 1

Methyl 4-hydroxy-3-methoxycinnamate (20.8 g) and potassium carbonate (30g) were suspended in dimethyl formamide (150 ml), and the suspension washeated to 90° C. Next, 4-chloro-1-butanol (21.6 g) was added dropwisethereto over 2 hours, and the mixture was stirred at 90° C. for 3 hours.Further, potassium carbonate (60 g) and 4-chloro-1-butanol (44 g) wereadded thereto. After confirming the completion of the reaction,dimethylformamide was evaporated under reduced pressure. The remainingsolid was dissolved in dichloromethane, and the solution was washed with5% hydrochloric acid and water. The solvent was evaporated under reducedpressure, and the obtained solid was purified by column chromatographyto obtain methyl 4-hydroxy-3-methoxycinnamate (24 g) as a yellow liquid.

¹H NMR (400 MHz, CDCl₃) δ: 1.75-1.79 (p, 2H), 1.95-1.99 (p, 2H),3.71-3.74 (t, 2H), 3.80 (m, 3H), 3.89 (t, 3H), 4.07-4.10 (t, 2H),6.29-6.33 (d, 1H), 6.85-6.87 (d, 2H), 7.04 (m, 1H), 7.07-7.09 (d, 2H),7.61-7.65 (d, 2H).

The reaction vessel was purged with nitrogen, and4-bromo-2-methoxyphenol (91 g), tert-butyl acrylate (69.0 g), andpotassium carbonate (92.9 g) were added thereto, and the mixture wassuspended in N-methylpyrrolidone (500 ml) at 25° C. Palladium acetate(101 mg) was added thereto at 25° C., and the mixture was stirred at100° C. for 1 hour, and subsequently at 110° C. for 1 hour and at 120°C. for 1 hour. After confirming the completion of the reaction, themixture was stirred, and water and 10% hydrochloric acid were addeddropwise thereto to neutralize the mixture to pH=6 to 7 whilemaintaining the inner temperature to lower than 25° C. The insolublesolid was separated by filtration and washed with toluene. The obtainedsolution was extracted twice with toluene, and the combined organicphase was washed with water and 10% saline. Toluene was evaporated underreduced pressure to obtain a crude product of tert-butyl4-hydroxy-3-methoxy cinnamate (142 g) as a brown viscous liquid.

Next, the obtained tert-butyl 4-hydroxy-3-methoxycinnamate (23 g),6-chlorohexyl methacrylate (20.0 g), and cesium carbonate (62 g) weredissolved in dimethyl sulfoxide (150 ml), and the solution was stirredat 60° C. for 3 hours. The reaction solution was cooled to roomtemperature, and 600 ml of water and 300 ml of dichloromethane wereadded thereto. The organic phase was separated and the aqueous layer wasextracted twice with 150 ml of dichloromethane. The organic phase wascombined, and washed with 10% hydrochloric acid, saturated aqueoussodium bicarbonate, and saturated saline, and then dried by the additionof sodium sulfate. Sodium sulfate was removed and the mixture waspurified by column chromatography (alumina/silica gel, dichloromethane),and the solvent was evaporated under a reduced pressure to obtaintert-butyl 4-(6-methacryloyloxy)-3-methoxycinnamate (34 g) as a whitesolid.

Next, the obtained tert-butyl 4-(6-methacryloyloxy)-3-methoxycinnamate(30 g) was dissolved in dichloromethane (300 ml) at 25° C., and 98%formic acid (60 ml) was added thereto at 25° C. The mixture was stirredat 40° C. for 2 hours, and after confirming the completion of thereaction, the inner temperature was cooled to 25° C. Dichloromethane wasevaporated under reduced pressure and then the solid was recrystallizedfrom methanol to obtain 4-(6-methacryloyloxy)-3-methoxycinnamic acid (25g) as a white solid.

Next, the obtained 4-(6-methacryloyloxy)-3-methoxycinnamic acid (18.6g), methyl 4-hydroxy-3-methoxycinnamate (15.2 g), andN,N-dimethylaminopyridine (0.7 g) were dissolved in ice-cooleddichloromethane (300 ml) under a nitrogen atmosphere.Diisopropylcarbodiimide (7.21 g) diluted in 20 ml of dichloromethane wasadded dropwise thereto, and the reaction solution was stirred at roomtemperature for 12 hours. The reaction solution was filtered, washedwith 10% hydrochloric acid and saturated saline, and then dried oversodium sulfate.

Sodium sulfate was removed, and the residue was purified by columnchromatography (alumina/silica gel, dichloromethane/ethyl acetate) andthen recrystallized from methanol to obtain DiCin-1 (28 g) as a whitesolid.

¹H NMR (400 MHz, CDCl₃) δ: 1.46-1.53 (p, 4H), 1.70-1.73 (p, 2H),1.85-1.91 (p, 4H), 1.94 (m, 3H), 1.99-2.02 (p, 2H), 3.80 (m, 3H), 3.89(m, 6H), 4.03-4.06 (t, 2H), 4.10-4.11 (t, 2H), 4.13-4.17 (t, 2H),4.27-4.30 (t, 2H), 5.55 (m, 1H), 6.09 (m, 1H), 6.27-6.32 (dd, 2H),6.84-6.88 (t, 2H), 7.05-7.09 (p, 4H), 7.59-7.65 (dd, 2H).

EI-MS: 624[M⁺]

In the same manner, the following compounds DiCin-2 to DiCin-12 weresynthesized.

Synthesis of Monomers for Copolymerization

9.01 g of butyl maleimidoacetate, 0.33 g of dibutyltin (IV) oxide, and9.14 g of tetradecanol were dissolved in 40 mL of toluene, followed bystirring for 15 hours while heating to reflux. The reaction solution wascooled to room temperature and 100 ml of toluene was added thereto. Themixture was subjected to liquid separation and washed with saturatedaqueous sodium bicarbonate and then with saturated saline. To thissolution was added sodium sulfate, and the mixture was dried. Sodiumsulfate was removed and the solvent was evaporated under reducedpressure to reduce the volume to about 50 ml, and 40 ml of hexane and 20ml of dichloromethane were added thereto. The mixture was purified bycolumn chromatography (alumina/silica gel, hexane/dichloromethane=2:1),the solvent was evaporated under reduced pressure, and the residue wasreprecipitated with methanol to obtain (V-1) (7.95 g) as a whitecrystal.

¹H-NMR (400 MHz, CDCl₃) δ: 0.88 (t, J=6.8 Hz, 3H), 1.15-1.40 (m, 22H),1.61-1.66 (tt, 2H), 4.14 (t, J=6.6 Hz, 2H), 4.15 (s, 2H), 6.79 (s, 2H)EI-MS: 351[M⁺]

Stearyl acrylate (V-2) (manufactured by Tokyo Chemical Industry Co.,Ltd.) was purchased and used.

N-(Butoxymethyl)acrylamide (V-3) (manufactured by Tokyo ChemicalIndustry Co., Ltd.) was purchased and used.

A compound (V-4) was synthesized according to the procedure described ina known document (Farmaco. Edizione Scientifica Vol. 22 (1967) 190,590-598).

Preparation of Cinnamic Acid Polymer (DCE-1) Example 13

1 part (10.0 mmol) of a compound represented by the formula (DiCin-1)was dissolved in 10 parts of ethyl methyl ketone to obtain a solution 1.To this solution 1 was added 0.01 parts of azobisisobutyronitrile(AIBN). The mixture was heated to reflux for 2 days under a nitrogenatmosphere to obtain a solution 2. Then, the solution 2 was addeddropwise to 60 parts of methanol under stirring, and the precipitatedsolid was filtered. The obtained solid was dissolved in 5 parts oftetrahydrofuran (THF), the solution was added dropwise to 120 parts ofice-cooled hexane under stirring, and the precipitated solid wasfiltered. The obtained solid was dissolved in 5 parts of THF, thesolution was added dropwise to 120 parts of ice-cooled methanol understirring, and the precipitated solid was filtered. The obtained solidwas dissolved in THF and then dried in vacuo to obtain a polymer(DCE-1).

Preparation of Cinnamic Acid Polymers (DCE-2) to (DCE-12)

In the same manner as for the cinnamic acid polymer (DCE-1), polymers(DCE-2) to (DCE-12) were obtained. The compositions of the respectivepolymers are as shown in Tables 1 and 2.

TABLE 1 Sample Blending amount (% by mole) name DiCin-1 DiCin-2 DiCin-3DiCin-4 DiCin-5 DiCin-6 Example 14 DCE-1 100 Example 15 DCE-2 100Example 16 DCE-3 100 Example 17 DCE-4 100 Example 18 DCE-5 100 Example19 DCE-6 100

TABLE 2 Sample Blending amount (% by mole) name DiCin-7 DiCin-8 DiCin-9DiCin-10 DiCin-11 DiCin-12 Example 20 DCE-7 100 Example 21 DCE-8 100Example 22 DCE-9 100 Example 23 DCE-10 100 Example 24 DCE-11 100 Example25 DCE-12 100

Preparation of Cinnamic Acid Polymer (DCEV-1) Example 26

0.9 parts (9.0 mmol) of the compound represented by the formula(DiCin-1) and 0.1 parts (1.0 mmol) of a compound represented by theformula (V-1) were dissolved in 10 parts of ethyl methyl ketone toobtain a solution 3. To this solution 3 was added 0.01 parts ofazobisisobutyronitrile (AIBN). The mixture was heated to reflux for 2days under a nitrogen atmosphere to obtain a solution 4. Then, thesolution 4 was added dropwise to 60 parts of methanol under stirring,and the precipitated solid was filtered. The obtained solid wasdissolved in 5 parts of tetrahydrofuran (THF), the solution was addeddropwise to 120 parts of ice-cooled hexane under stirring, and theprecipitated solid was filtered. The obtained solid was dissolved in 5parts of THF, the solution was added dropwise to 120 parts of ice-cooledmethanol under stirring, and the precipitated solid was filtered. Theobtained solid was dissolved in THF and then dried in vacuo to obtain apolymer (DCEV-1).

Preparation of Cinnamic Acid Polymers (DCEV-2) to (DCEV-50)

In the same manner as for the cinnamic acid polymer (DCEV-1), polymers(DCEV-2) to (DCEV-50) were obtained. The compositions of the respectivepolymers are as shown in Tables 3 and 4.

TABLE 3 Sample Blending amount (% by mole) Example name DiCin-1 DiCin-2DiCin-3 DiCin-4 DiCin-5 DiCin-6 V-1 V-2 V-3 V-4 27 DCEV-1 90 10 28DCEV-2 85 15 29 DCEV-3 80 20 30 DCEV-4 80 20 31 DCEV-5 80 20 32 DCEV-680 20 33 DCEV-7 80 20 34 DCEV-8 80 20 35 DCEV-9 80 20 36 DCEV-10 80 2037 DCEV-11 80 20 38 DCEV-12 80 20 39 DCEV-13 80 20 40 DCEV-14 80 20 41DCEV-15 80 20 42 DCEV-16 80 20 43 DCEV-17 80 20 44 DCEV-18 80 20 45DCEV-19 80 20 46 DCEV-20 80 20 47 DCEV-21 80 20 48 DCEV-22 80 20 49DCEV-23 80 20 50 DCEV-24 80 20 51 DCEV-25 80 20 52 DCEV-26 80 20

TABLE 4 Sample Blending amount (% by mole) Example name DiCin-7 DiCin-8DiCin-9 DiCin-10 DiCin-11 DiCin-12 V-1 V-2 V-3 V-4 53 DCEV-27 80 20 54DCEV-28 80 20 55 DCEV-29 80 20 56 DCEV-30 80 20 57 DCEV-31 80 20 58DCEV-32 80 20 59 DCEV-33 80 20 60 DCEV-34 80 20 61 DCEV-35 80 20 62DCEV-36 80 20 63 DCEV-37 80 20 64 DCEV-38 80 20 65 DCEV-39 80 20 66DCEV-40 80 20 67 DCEV-41 80 20 68 DCEV-42 80 20 69 DCEV-43 80 20 70DCEV-44 80 20 71 DCEV-45 80 20 72 DCEV-46 80 20 73 DCEV-47 80 20 74DCEV-48 80 20 75 DCEV-49 80 20 76 DCEV-50 80 20

Preparation of Alignment Layer and Liquid Crystal Display ElementExample 77

The cinnamic acid polymer (DCE-1) was dissolved in cyclopentanone to be1.0% and the solution was stirred at room temperature for 10 minutes.Then, the solution was applied onto a glass plate as a substrate, usinga spin coater, and dried at 100° C. for 3 minutes. Then, the surface wasvisually observed and as a result, it was found that a polymer wasuniformly applied on the glass plate to form a smooth film.

Next, irradiation of linear polarized and parallel light of visibleultraviolet light (wavelength: 313 nm, irradiation intensity: 8 mW/cm²)was performed onto the coated glass plate using an ultrahigh-pressuremercury lamp via a wavelength cut filter, a band-pass filter, and apolarizing filter in a direction of 45 degrees with respect to thesubstrate. The irradiation dose was 100 mJ/cm². The thickness of thefilm was measured and found to be about 50 nm.

A liquid crystal cell was fabricated by using the coated glass plateprepared by the method above. The gap between the plates was set to 10μm and the two glass plates were bonded in the anti-parallel direction.Next, a nematic liquid crystal mixture having a negative dielectricanisotropy with a composition described below was charged into the cellat a temperature just exceeding a transparent point (Tc=84.4° C.), andthen cooled to room temperature. A polarizing plate was placed on thetop and the bottom of the liquid crystal cell, and a back light wasplaced therebelow. The light transmittance was changed by rotating theliquid crystal cell by 90 degrees and dark-light contrast was clearlyobserved and there was no abnormal domain and alignment non-uniformity,from which it was confirmed that the liquid crystals were normallyaligned. The tilt angle of the liquid crystal in the cell was opticallymeasured by a crystal rotation method, and the pretilt angle was foundto be 1 degree. A voltage of 5 V was applied to this liquid crystal cellfor an application time of 60 microseconds at a span of 167milliseconds, and the voltage holding ratio after 167 milliseconds fromthe release of the voltage was measured by means of “VHR-AMP01”manufactured by TOYO Corporation at 23° C., and as a result, the voltageholding ratio (VHR) was found to be 99.4%.

Hereinafter, in the same manner as the cinnamic acid polymer (DCE-1),with respect to (DCE-2) to (DCE-12), and (DCEV-1) to (DCEV-50),alignment layers were fabricated and liquid crystal cells werefabricated. The measurement results of the irradiation doses of linearpolarized light, liquid crystal alignment property, pretilt angle, andVHR are shown in conjunction in Table 5. For the irradiation dose oflinear polarized light, an irradiation dose of less than 120 mJ/cm² wasassumed to be O (good), an irradiation dose of 120 mJ/cm² or more andless than 300 mJ/cm² was assumed to be (acceptable), and an irradiationdose of 300 mJ/cm² or more was assumed to be x (poor). For the liquidcrystal alignment property, when the presence or absence of the abnormaldomain and alignment non-uniformity of the liquid crystal cell wasobserved, a case where there was no place where the abnormal domain andalignment non-uniformity are present was assumed to be O (good), a casewhere there was the abnormal domain and alignment non-uniformity in twoor less places was assumed to be Δ (acceptable), and a case where therewas the abnormal domain and alignment non-uniformity in three or moreplaces was assumed to be x (poor). For the pretilt angles, the pretiltangles were optically measured by a crystal rotation method, and thus, acase where the pretilt angle was 80 degrees or more and less than 90degrees was denoted as V, and a case where the pretilt angle was 0degree or more and less than 15 degrees was denoted as P. For VHR, acase where the VHR was 98% or more was denoted as O (good), a case wherethe VHR was 95% or more and less than 98% was denoted as (acceptable),and a case where the VHR was 95% or less was denoted as x (poor).

TABLE 5 Irradiation dose Liquid crystal Sample of linear polarizedalignment Pretilt name light property angle VHR Example DCE-1 ◯ ◯ P ◯ 77Example DCE-2 ◯ ◯ P ◯ 78 Example DCE-3 ◯ ◯ P ◯ 79 Example DCE-4 ◯ ◯ P ◯80 Example DCE-5 ◯ ◯ P ◯ 81 Example DCE-6 ◯ ◯ P ◯ 82 Example DCE-7 ◯ ◯ P◯ 83 Example DCE-8 ◯ ◯ P ◯ 84 Example DCE-9 ◯ ◯ P ◯ 85 Example DCE-10 ◯◯ P ◯ 86 Example DCE-11 ◯ ◯ P ◯ 87 Example DCE-12 ◯ ◯ P ◯ 88

TABLE 6 Irradiation Liquid dose of crystal Sample linear polarizedalignment Pretilt name light property angle VHR Example 89 DCEV-1 ◯ ◯ V◯ Example 90 DCEV-2 ◯ ◯ V ◯ Example 91 DCEV-3 ◯ ◯ V ◯ Example 92 DCEV-4◯ ◯ V ◯ Example 93 DCEV-5 ◯ ◯ P ◯ Example 94 DCEV-6 ◯ ◯ P ◯ Example 95DCEV-7 ◯ ◯ V ◯ Example 96 DCEV-8 ◯ ◯ V ◯ Example 97 DCEV-9 ◯ ◯ P ◯Example 98 DCEV-10 ◯ ◯ P ◯ Example 99 DCEV-11 ◯ ◯ V ◯ Example 100DCEV-12 ◯ ◯ V ◯ Example 101 DCEV-13 ◯ ◯ P ◯ Example 102 DCEV-14 ◯ ◯ P ◯Example 103 DCEV-15 ◯ ◯ V ◯ Example 104 DCEV-16 ◯ ◯ V ◯ Example 105DCEV-17 ◯ ◯ P ◯ Example 106 DCEV-18 ◯ ◯ P ◯ Example 107 DCEV-19 ◯ ◯ V ◯Example 108 DCEV-20 ◯ ◯ V ◯ Example 109 DCEV-21 ◯ ◯ P ◯ Example 110DCEV-22 ◯ ◯ P ◯ Example 111 DCEV-23 ◯ ◯ V ◯ Example 112 DCEV-24 ◯ ◯ V ◯Example 113 DCEV-25 ◯ ◯ P ◯ Example 114 DCEV-26 ◯ ◯ P ◯

TABLE 7 Irradiation Liquid dose of crystal Sample linear polarizedalignment Pretilt name light property angle VHR Example 115 DCEV-27 ◯ ◯V ◯ Example 116 DCEV-28 ◯ ◯ V ◯ Example 117 DCEV-29 ◯ ◯ P ◯ Example 118DCEV-30 ◯ ◯ P ◯ Example 119 DCEV-31 ◯ ◯ V ◯ Example 120 DCEV-32 ◯ ◯ V ◯Example 121 DCEV-33 ◯ ◯ P ◯ Example 123 DCEV-34 ◯ ◯ P ◯ Example 124DCEV-35 ◯ ◯ V ◯ Example 125 DCEV-36 ◯ ◯ V ◯ Example 126 DCEV-37 ◯ ◯ P ◯Example 127 DCEV-38 ◯ ◯ P ◯ Example 128 DCEV-39 ◯ ◯ V ◯ Example 129DCEV-40 ◯ ◯ V ◯ Example 130 DCEV-41 ◯ ◯ P ◯ Example 131 DCEV-42 ◯ ◯ P ◯Example 132 DCEV-43 ◯ ◯ V ◯ Example 133 DCEV-44 ◯ ◯ V ◯ Example 134DCEV-45 ◯ ◯ P ◯ Example 135 DCEV-46 ◯ ◯ P ◯ Example 136 DCEV-47 ◯ ◯ V ◯Example 137 DCEV-48 ◯ ◯ V ◯ Example 138 DCEV-49 ◯ ◯ P ◯ Example 139DCEV-50 ◯ ◯ P ◯

From the above results, it can be seen that an alignment layer, whichallows a small irradiation dose of linear polarized light, and has asuperior liquid crystal alignment property and a superior ability tocontrol the pretilt, and exhibits a high voltage holding ratio, can beobtained by the cinnamic acid polymerized product obtained bypolymerizing the cinnamic acid derivatives of the present invention.

Comparative Example 1

For comparison, cinnamic acid derivatives (D-1) and (D-3) weresynthesized, and thus, by the same method as in Example 13, cinnamicacid polymers (CE-1) to (CE-2) and (CEV-1) to (CEV-8) were prepared.

TABLE 8 Sample Blending amount (% by mole) name D-1 D-3 V-1 V-2 V-3 V-4Comparative CE-1 100 Example 1 Comparative CE-2 100 Example 2Comparative CEV-1 80 20 Example 3 Comparative CEV-2 80 20 Example 4Comparative CEV-3 80 20 Example 5 Comparative CEV-4 80 20 Example 6Comparative CEV-5 80 20 Example 7 Comparative CEV-6 80 20 Example 8Comparative CEV-7 80 20 Example 9 Comparative CEV-8 80 20 Example 10

Furthermore, by the same method as in Example 77, an alignment layer wasfabricated, and various measurements were conducted and the resultstherefrom are shown in Table 9.

TABLE 9 Liquid crystal Sample Irradiation dose of alignment Pretilt namelinear polarized light property angle VHR Comparative CE-1 Δ ◯ P ΔExample 11 Comparative CE-2 Δ ◯ P Δ Example 12 Comparative CEV-1 Δ Δ V ◯Example 13 Comparative CEV-2 Δ Δ V ◯ Example 14 Comparative CEV-3 Δ ◯ PΔ Example 15 Comparative CEV-4 Δ ◯ P Δ Example 16 Comparative CEV-5 Δ ΔV ◯ Example 17 Comparative CEV-6 Δ Δ V ◯ Example 18 Comparative CEV-7 Δ◯ P Δ Example 19 Comparative CEV-8 Δ ◯ P Δ Example 20

Therefore, it can be seen that a liquid crystal alignment layer, and adisplay element using the liquid crystal alignment layer, each of whichallows a small irradiation dose of linear polarized light during theproduction, and has the effects, such as having a superior ability tocontrol the alignment of the liquid crystals and the pretilt angles, andexhibits a high voltage holding ratio (VHR), can be obtained by usingthe compound (cinnamic acid derivative) of the present invention and apolymer thereof.

INDUSTRIAL APPLICABILITY

The present invention provides a liquid crystal alignment layer which isefficiently provided with an alignment property at a low dose ofirradiation of polarized light during the production, and has a superiorability to control the alignment of the liquid crystals and the pretiltangles, and a high voltage holding ratio (VHR); a polymer used for theliquid crystal alignment layer; a compound constituting the polymer; aliquid crystal display element using the liquid crystal alignment layer;and an optical anisotropic body using the polymer.

The invention claimed is:
 1. A polymer constituted with a cured product,wherein the cured product has a structural unit represented by thegeneral formula (V):

wherein Sp¹ and Sp² each represent a spacer unit, A⁰¹ and A⁰² eachindependently represent a group selected from the group consisting of:(a) a trans-1,4-cyclohexylene group wherein one methylene group or twoor more non-adjacent methylene groups present in this group may besubstituted with —O—,—NH—, or —S—, (b) a 1,4-phenylene group wherein oneor two or more —CH═'s present in this group may be substituted with —N═,and (c) a 1,4-cyclohexenylene group, a 2,5-thiophenylene group, a2,5-furanylene group, a 1,4-bicyclo(2.2.2)octylene group, anaphthalene-1,4-diyl group, a naphthalene-2,6-diyl group, adecahydronaphthalene-2,6-diyl group, and a1,2,3,4-tetrahydronaphthalene-2,6-diyl group, in which the group (a),(b), or (c) may be each unsubstituted or may have one or more hydrogenatoms substituted with a fluorine atom, a chlorine atom, a cyano group,a methyl group, or a methoxy group, X¹, X², Y¹ and Y² each independentlyrepresent a hydrogen atom, a fluorine atom, a chlorine atom, a cyanogroup, or an alkyl group having 1 to 20 carbon atoms, but a hydrogenatom in the alkyl group may be substituted with a fluorine atom, and oneCH₂ group or two or more non-adjacent CH₂ groups may be substituted with—O—, —CO—O—, —O—CO—, —CH═CH—or a combination thereof, Z is representedby the general formula (IIa) or (IIb):

in which the dashed line represents a bond to a carbon atom, to which Zis bonded, and R¹ R² each independently represent a hydrogen atom or alinear or branched alkyl group having 1 to 30 carbon atoms, wherein one—CH₂—group or two or more non-adjacent —CH₂— groups in R¹ and R² may besubstituted with —O—, —CO—, —CO—O—, —O—CO—, —CO—NH—, —NH—CO—, —NCH₃—,—CH═CH—, —CF═CF—, —C≡C—, or a combination thereof, wherein one or two ormore —CH₂— groups in R¹ and R² may be each independently substitutedwith a cycloalkyl group with a 3- to 8-membered ring, and a hydrogenatom in R¹ and R² may be substituted with an alkyl group having 1 to 20carbon atoms, a cyano group, or a halogen atom, W represents —O— or—NR³—, in which R³ represents a hydrogen atom, a linear or branchedalkyl group having 1 to 20 carbon atoms, or a cycloalkyl group with a 3-to 8-membered ring, which may have the alkyl group interposed therein asa linking group, a hydrogen atom in the alkyl group may be unsubstitutedor may be substituted with a fluorine atom or a chlorine atom, ahydrogen atom in the cycloalkyl group may be unsubstituted or may besubstituted with an alkyl group having 1 to 10 carbon atoms, an alkoxygroup having 1 to 10 carbon atoms, a fluorine atom, or a chlorine atom,and r and t each independently represent 1 or 2, M_(b) and M_(d) eachrepresent a monomer unit of the polymer, y and w each represent a molarfraction of the copolymer, each satisfying 0<y≤1 and 0≤w<1, n represents4 to 100,000, the order in which M_(b) and M_(d) are arranged may be thesame as or different from that shown in the formula, and the monomerunits of M_(b) and M_(d) may be each independently constituted with oneor two or more different units.
 2. The polymer according to claim 1,wherein M_(b) in the general formula (V) represents any one or moreselected from the group consisting of the general formulae (QIII-A-1) to(QIII-A-17):

wherein the dashed line represents a bond to Sp¹, R's independentlyrepresent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,and any hydrogen atom in each of the structures may be substituted witha fluorine atom, a chlorine atom, a methyl group, or a methoxy group. 3.The polymer according to claim 1, wherein M_(d) in the general formula(V) represents any one or more selected from the group consisting of thegeneral formulae (QIII-1) to (QIII-17):

wherein the dashed line represents a bond to a hydrogen atom or amonovalent organic group, R's independently represent hydrogen or analkyl group having 1 to 5 carbon atoms, and any hydrogen atom in each ofthe structures may be substituted with a fluorine atom, a chlorine atom,a methyl group, or a methoxy group.
 4. The polymer according to claim 3,wherein in the general formulae (QIII-1) to (QIII-17), the monovalentorganic group is represented by the general formula (QIV):—S_(a)—V_(a)  (QIV) wherein the dashed line represents a bond to anM_(d), S_(a) represents a structure represented by the general formula(IV),

wherein in Sp¹, the left dashed line represents a bond to L and theright dashed line represents a bond to A⁰¹, and in Sp², the left dashedline represents a bond to W and the right dashed line represents a bondto A⁰², in Sp¹ and Sp², independently, Z¹, Z² and Z³ each independentlyrepresent a single bond, —(CH₂)_(u) in which u represents 1 to 20,—OCH₂—, —CH₂O—, —COO—, —OCO—, —CH═CH—, —CF═CF—, —CF₂O—, —OCF₂—,—CF₂CF₂—, or —C≡C—, and one or more of the non-adjacent CH₂ groups inthese groups may be independently substituted with —O—, —CO—, —CO—O—,—O—CO—, —Si(CH₃)₂—O—Si(CH₃)₂—, —NR—, —NR—CO—, —CO—NR—, —NR—CO—O—,—O—CO—NR—, —NR—CO—NR—, —CH═CH—, —C≡C—, or —O—CO—O—, in which R'sindependently represent hydrogen or an alkyl group having 1 to 5 carbonatoms, and A¹ and A² each independently represent a group selected fromthe group consisting of: (a) a trans-1,4-cyclohexylene group, in whichone methylene group or two or more non-adjacent methylene groups presentin this group may be substituted with —O—, —NH—, or —S—, (b) a1,4-phenylene group in which one or two or more —CH═'s present in thisgroup may be substituted with —N═, and (c) a 1,4-cyclohexenylene group,a 2,5-thiophenylene group, a 2,5-furanylene group, a1,4-bicyclo(2.2.2)octylene group, a naphthalene-1,4-diyl group, anaphthalene-2,6-diyl group, a decahydronaphthalene-2,6-diyl group, and a1,2,3,4-tetrahydronaphthalene-2,6-diyl group, in which the group (a),(b), or (c) may be each unsubstituted or may have one or more hydrogenatoms substituted with a fluorine atom, a chlorine atom, a cyano group,a methyl group, or a methoxy group, and p represents 0 or 1, and qrepresents 0, 1, or 2, and V_(a) represents a structure represented bythe following general formula (VI):

wherein the dashed line represents a bond to S_(a), Z⁴, Z⁵, Z⁶ and Z⁷each independently represent a single bond, —(CH₂)_(u)— in which urepresents 1 to 20, —OCH₂—, —CH₂O—, —COO—, —OCO—, —CH═CH—, —CF═CF—,—CF₂O—, —OCF₂—, —CF₂CF₂—, or —C≡C—, but one or more of the non-adjacentCH₂ groups in these substituents may be independently substituted with—O—, —CO—, —CO—O—, —O—CO—, —Si(CH₃)₂—O—Si(CH₃)₂—, —NR—,—NR—CO—, —CO—NR—,—NR—CO—O—, —O—CO—NR—, —NR—CO—NR—, —CH═CH—, —C≡C—, or —O—CO—O— in whichR's independently represent hydrogen or an alkyl group having 1 to 5carbon atoms, A³, A⁴, A⁵ and A⁶ each independently represent a groupselected from the group consisting of: (a) a trans-1,4-cyclohexylenegroup wherein one methylene group or two or more non-adjacent methylenegroups present in this group may be substituted with —O—, —NH—, or —S—,(b) a 1,4-phenylene group wherein one or two or more —CH═'s present inthis group may be substituted with —N═, and (c) a 1,4-cyclohexenylenegroup, a 2,5-thiophenylene group, a 2,5-furanylene group, a1,4-bicyclo(2.2.2)octylene group, a naphthalene-1,4-diyl group, anaphthalene-2,6-diyl group, a decahydronaphthalene-2,6-diyl group, or a1,2,3,4-tetrahydronaphthalene-2,6-diyl group, in which the group (a),(b), or (c) may be each unsubstituted or may have one or more hydrogenatoms substituted with a fluorine atom, a chlorine atom, a cyano group,a methyl group, or a methoxy group, r1, s1, t1, and u1each independentlyrepresent 0 or 1, and R¹² represents hydrogen, fluorine, chlorine, acyano group, or an alkyl group having 1 to 20 carbon atoms, a hydrogenatom in the alkyl group may be substituted with a fluorine atom, and oneCH₂ group or two or more non-adjacent CH₂ groups may be substituted with—O—, —CO—O—, —O—CO—, —CH═C—, or a combination thereof.
 5. A liquidcrystal alignment layer for a vertical alignment mode liquid crystaldisplay element, using the polymer according to claim
 1. 6. A verticalalignment mode liquid crystal display element using the liquid crystalalignment layer according to claim
 5. 7. A liquid crystal alignmentlayer for a horizontal alignment mode liquid crystal display element,using the polymer according to claim
 1. 8. A horizontal alignment modeliquid crystal display element using the liquid crystal alignment layeraccording to claim
 7. 9. A liquid crystal alignment layer for an opticalanisotropic body, using the polymer according to claim
 1. 10. An opticalanisotropic body constituted with a polymer of a polymerizable liquidcrystal composition, wherein polymerizable liquid crystal molecules inthe polymerizable liquid crystal composition are aligned using theliquid crystal alignment layer according to claim 9.